The influence of chronic low back pain on lumbar paravertebral muscle activity during functional tasks

Abstract

Introduction: There is evidence that patients with chronic low back pain present an increased trunk muscle activity during gait. However, it is not known whether this maladaptive behavior is present across a range of functions within a given patient. Objective: The aim of this study was, therefore, to analyse the back muscle activity of low back pain patients during five functional tasks, and compare to asymptomatic controls. Methods: Forty patients with chronic low back pain (LBP) and 40 asymptomatic controls were assessed via electromyography of the lumbar longissimus, iliocostalis and multifidus muscles during picking up and leaving an object on the ground, sitting down and standing up, and climbing a stair. Group comparison were based on calculations of mean differences and 95% CIs. Results: There were no group differences with respect to gender, weight, height and BMI. The LBP group presented a mean of 6 points (SD=1.5) in the numeric pain scale, 40% (SD=11.9) of disability (ODI), 45 points (SD=7.3) of kinesiophobia (TAMPA Scale) and 53.5 points (SD=10.6) in the Örebro Questionnaire. In 29 of the 30 analyzes, including both sides of three muscles in five tasks, the participants with chronic low back pain presented a statistically significant (p<0.05) higher mean of superficial electromyographic activity than the asymptomatic controls. Conclusion: Patients with chronic low back pain show increased back muscle activity regardless of the functional task. Our findings conflict with the idea that stimulating muscle activity would benefit patients with chronic low back pain.